Composition and process for treating metal surfaces



J. c. LUM 2,516,008

COMPOSITION AND PRocEss FOR TREATING METAL sURFAcEs July 18, 1950 Rm OVI TNIL N E. R VC O mn L n m J 'WITNESSES:

Patented `uly 18, I195() COMPOSITION PROCESS FOR TREATIN G METALSURFACES John C. Lum, East Orange, N.`J., assignor to WestinghouseElectric Corporation, East Pittsburgh, Pa., a Vcorporatonof PennsylvaniaApplication June 19, 194s, seri1N0.34,11o

9 claims. (clins-6.15)

y This invention relates to the art of producing y corrosion resistantphosphate coatings on the sur- `faces lof iron, Zinc, cadmium, aluminum,and

other metals and alloys.

' It, is a common and extensive practice at Athe present time to treatthesurfaces of metals, such as iron,`"z`inc,` cadmium and aluminum andthe like,` with phosphate solutions that react' with the metal `surfaceto lproduce tl'lereon'a'` protective phosphate' coating.'V Suchphosphate coatings provide for a high corrosion resistance' andk'form anexcellent base' for paints `or other subsequently applied organicfinishes.` i 1 vIt has been known" that for a` given metal the surfacesvary considerably in their degree 'of 'r'eactivity to the phosphatesolutions so that nonuniiorm and widely varying phosphate coatingsresult. On' vsome metals, such, for instance,r as zinc the rfornratior'llof a protective phosphate coatingV is usually difficult because of itsinherent acteristics of phosphate' coatings on zincis `much poorer thansecured withviron or steel. However, even between sheets of steel, whichsas a whole react'morev completely and more uniformlywith phosphatesthan does zinc, there vmay beaconsiderable variation in the'amunt landprotective quality of the applied phosphate coating not `only betweendifferentlsheet's but with different areas on a single sheet. `It haslong been held desirable to be able to treat metal surfaces, regardlessoff their inherent characteristics, to produce a? high quality phosphatecoating that is rela-` tively uniform at all times.

The prior art practicesfor producing protective phosphate coatings onmetals, such, for example, as sheet steel comprised the followingessential steps: first, vthe cleaning of the sheet in an alkalinesolution consisting, for instance, of 'soda ash dissolved in water;secondly, the applicationof the phosphate coating composition to thesheet steel fora period of time of the order of onemin ute; and lastly,applyingY a dilute water solution of chromic acid to sealthe"v phosphatecoating passivitmand the uniformity and protective char- H5`f`i'.9,2'74,` Vled December 21, 1944, now "Patent y2,456,947, andr510,251, filed lNovember 13, 1943, `now abandoned, it has been .furthersuggested that the activating compositionbe combined with the alkalinemetal cleaner so that the metal surfaces may` `be simultaneously cleanedand. acti- ,vated. The advantages of such a combined op,-

eration :are that the conventional processing equipment need not be`changed and the time for complete treatment of a piece of metal is notincreased over that required `when no activating composition isproduced. However,` it has been discovered that when the activatingcomposition is combined with the` alkaline cleaner, ,the Aactivatingcomposition deteriorates rapidlyr at temperatures above F.

whereas the` alkali cleaner itself is most effective atltemperatures offromr F.;to 212 F. Thus,

`it lhasbeen found that the use of the alkaline cleaner containing theactivating composition at a temperature of 200 1F. results in theactivating eifect disappearing in aboutan hour. Itis obviouslybcthuneconomical and undesirable. to repleriishV the activ-atingcomposition frequently,

particularly `since vthe changein its effect becomes noticeable in :lessthan an hour, and therefore erratic'results may occur. V 1 "The, object.of this invention` is, to provide a composition containing both analkaline cleaning component 'and` an activating component, plus a,stabilizerA so that the composition has a llong life atelevatedtemperatures.

.A `further .object of the invention is to provide l ,af processforeffectively and reliably treating the :surfaces of Inetal members,wherebyy to simul. taneo'uslyfclean and activate them atan elevatedtemperature. f ,.Qther objects of the invention will, in partbeobviousland will, in part, appear hereinafter.

" For abetter understanding offthe nature and objects `of the invention,reference should be had tofthe following detailed description .and drawfing, lin which the single gure is a view in elevation `tio" ofanapparatus for carrying out the invento provide from 0.1% to of theactivating composition in solution and from i2 to '10 .ounces per gallonof the alkali cleaner composition.

The alkaline composition may be any suitable alkali metal compoundwhich, when .in water Solution, produces a pH of between 1.0 and 12.5,:y

and is effective in removing surface dirt from metal surfaces. Suitablealkaline-compounds are soda ash, sodium bicarbonate, sodium silicates,trisodiurn phosphate, sodium hydroxide, borax, Land mixtures thereof.Also, there maybe employed l,alkaline soaps Vof the alkali metals, andammonia or ,amine soaps, such for instance, as the-reactionproduct ofammonia or triethanolamine withI oleic or stearic acid, palmitic acid orotherfatty acids having 16 carbon atoms. The soaps maybe employed in theform of an emul- 'sionwith a hydrocarbon solvent, such as kerosene.

Theactivating composition is prepared by dissolving in waterfrom"0.005to 20 parts by weight a watersoluble compound of at least one 'metal ofthe lgroup consisting of-titanium, zirconium, `lead or tin, all of ithese metals being in' group IV o f the periodic table, with from 80 to100 parts by weight of disodium orthophosphate. The ,aqueous solutionsoprepared is evaporated to drynessand' the dried residue possesses thevcharacteristics of activating metal surfaces when dissolved in water orWater containing an alkali that does not exced a pH 'of 1,2;5, or'waterthat is not acid.

'Examples of water soluble compounds of titanium, zirconium, tin andlead, that-have been foundA satisfactory for producing' the activatingcomposition are titanium carbide, titaniumtetrachloride, titaniumtrichloride, :titanium hydroxide, titanium nitride, titanium potassiumoxalate, titanium dioxide, zirconium chloride, zirconium sulphate, leadacetate, tin tetrachloride andstannic sulphate. Since onlyrelativelysmall amounts of any titanium, zirconium, lead and tincompound need be dissolved, the compounds selected need be lonlyslightly soluble in water to be suitable. Since the weight proportion ofthe required `metal present varies from compound to compound, the amountof metallic "compound employed should be selected accordingly.

As an example of the preparation of the activating composition, in150pounds of watervthere was dissolved 100 pounds ofdisodium orthophosphateand 3 pounds titanium potassium oxalate. The solution was heated toabout 75C. and slowly evaporated to a dry residue. The dry residue was apowerful activator for metal surfaces and was ready for use foractivating metals by simply dissolving it in Water. l

Suitable organic acids for stabilizing the4 activating compositions arewater soluble organic carboxylic acids having a carboxyl radicalattached directly to an aliphatic group. Examples of such acids arecitric acid, tartaric acid, oxalic acid, acetic acid, propionicacid,'succinic acid, maleic acid, lactic acid and glycolic acid. Acidsin whichthe carboxyl group is directly attached to an aryl group such,for example, as benzoic acid have been found to be ineiective. Theamount of the acid should comprise at least 2% of the weight of thedried activating composition, and preferably be of the order of 10%. Theorganic acid may be present in an amount equal tov50% of the weight ofthe activating composition. ,The maximum amount of any particularorganic acid usable may be limited by its relative solubility in thesolution.

The compositions combining the alkaline cleaning composition, theactivating composition and the-organic acid stabilizer may be prepared,withoutany water-or only a small amount of Water, as

.a .composite mixture which may be shipped and need .only bedissolved insuicient water to produce a relatively dilute solution capable ofsimultaneously cleaning and activating metal surfaces at l.elevatedtemperatures. If desired, the three components may be shipped asmixtures of any two or else may be combined at the time .the aqueousIsolution is prepared at the time the metal is being treated.

Theorganic acid stabilizer cannot be incorporated with the activatedcomposition when it is being made by evaporation to a `dry residue sinceitlhas'been found that the resulting dry residue containing the organicacid is useless for its intended purpose if so prepared.

The'followingtypical examplesof compositions whose aqueous solutions inthe proportions of from 2'to 10 ounces of .the alkaline cleaner pergallon of water will function .extremely effectively to simultaneouslyclean and activate metal surfaces:

Eample I Parts by weight Activating composition (containing 5% titanium)2 Soda ash 6 Citric acid '0.2

Example II Parts by weight Activating composition (containing 1%titanium) 3 Sodium sesquisilicate 10 Tartaric acid 0.6

Example HI Parts by .Weight Activating composition (containing 10% tiytanium) 6 Trisodium phosphate 13 Oxalic acid 1.0

Example IV I Parts by Weight Activating composition (containing 1%titanium) 0.2 Soda ash 5 Trisodium phosphate '5 Lactic acid 0.01 yEwample V Parts by weight Activating composition (containing 1% tita-Thecompositions ineach-of the above examples may be dissolved in waterinthe amount of from 2 to, 10 ounces of the alkalinecomposition per`gallon and providing a pI-Iof from-$to 12.5

may be employedl at any"'desired temperature,

preferably above 160 F. A composition similar to Example I was used forover a week at near boiling temperature without loss offa-ctivity. Thesame solution withoutthe citric acid-wasincapable of activatingmetalfsurfaces shortly after `one hour at 200 F.

sheets of aluminum andl aluminum alloys,` and alloys in which thesemetals predominate. The time of application of thehot cleaning andactivating solution need `not be long. `A few minutes isordinarilysuiicient to remove surface grease and loose oxides and dirt.The composition may be applied by spraying, lif necessary, under highpressure to remove the more `adherent particles o-f dirt. Ifthe metal isbadly rusted or oxidized or scaled, it may be necessary towire brush oracid etch the metal before it is subj ected to the activating alkalinesolutions o f this invention. l

After the metal surface has been treated with the component alkalinecleaner and activating composition so that it is clean and in a highlyactive state, it may be subjected to an appropriate phosphatecoatingsolution.v A suitable solution for treating steel or other metalsis thev follow- Manganese phosphate pounds `1.75 Phosphoric acid (83%)do 5 Sodium` nitrate do 0.5

Cupric nitrate 1 ounces-- .25 Waterto make one gallon. l

Iron per cent 0.25 Zinc phosphate do 0.04 Sodium nitrate .do l I 0.5Phosphoric acid (85%) `do. 1.0 Remainder Water Numerous other solutionsfor producing phosphate coatings are known in the art and it is believedunnecessaryto list them in detail; lEssentially, such solutionscompriseia phosphate, free phosphoric acid and an oxidizing agent, suchas sodium or potassium nitrate or nitrite.` They may be applied byspraying, brushing or dipping of the metal surfaces thereim' l y Whenapplied `to the activated and cleaned surfaces, such phosphate coatingcompositions will produce protective phosphate coatings thereon within ashort period ,of time, about seconds being suiiicient. However, thegreatest advantage derived from activation is the fact that metalsurfaces acquire a highly uniforml phosphate coating. In most cases thephosphate coatings are almost velvety in appearance.` Under themicroscope they exhibit a very ne crystalline structure. There are nobare spots, Inor 'do they show a gross blotchy effect which often`occurswith metal-that has notlbeenlactivatedd- A f Referring tothesingle figure ofthe drawing, there is illustrated an apparatus I0 forcarrying outthe complete process disclosed herein. The apparatuscomprises a track`I2 for'supporting a plurality of roller mountedhangers I3 on'which depend metal members Ill` to be provided-with aprotective phosphate coating. The members initially are moved intoVposition over a tank I6 and drop therein for immersion-or for sprayingif desired, in a solution i 8 having a pH of from 10 to 12.5, in whichsolution the membersld are cleaned and activated simultaneously. Thesolution I8 comprises an alkaline cleaner, the activating compositionand the organic stabilizer. The solution is used hot, that is between160 F. and boiling, and, therefore, operates rapidly andeifectively toremove any surface contamination, such as grease and dirt. It has beenfound that while being cleaned the metal is most responsive toactivation so, that the highest degree of lactivation of the metal takesplace under these conditions. l i

After being treated with thesolution I8 until clean, usually in a shortperiod of time, the clean and activated metal member I4 is subjected `toa water rinse in tank 20. The water rinse will remove any material whosepresence is not desired in subsequently applied phosphate coatingcompositions. Immediately after rinsing 01min some cases dispensing withthe Water rinse, the

member I4 is conveyed to a tank 22 containing a phosphate coatingcomposition 24. The phosphate composition reacts rapidly and uniformlyover the entire pretreated surface of the vmemf' ber I6 to producethereon a smooth, fine, uniform protective phosphate coating. Thence,the coated member I4 may be moved along the con- Veyer I2 to a secondwater rinse tank 26. rThe last step in the process is to dip the memberI4 in a tank 28 containing a hot aqueous solution 30 of chromic acid inthe proportion of 7.5 ounces of chromic acid to gallons of water. Thechromic acid functions so that ina-'few seconds it seals the phosphatecoating thereby improving its corrosion' resistance. If the chromic acidsolution is about 200 'E., the heat imparted to the members I4 isordinarily sufficient to dry them by simple exposure to the `atmosphere.lin some cases, however, the members may be conveyed to a drying ovenwherein any water on the surface is completely evaporated leaving a. drysealed phosphate coating having the utmost protective value. i

The apparatus shown in the gure corresponds tothat vconventionallyemployed at the present time for phosphate coating without theV use ofan activating pretreatment. It will be apparent that by being able tocombine the cleaning and activating solution to effect a'simultaneouscleaning and activation of metal in the single tank I6, no changes inthe apparatus are re'- quired. Otherwise, the` necessity for a separatetank for the solution for activating the metal surfaces would requireextensive changes, such asrebuilding of a conveyer and shifting oftanks. Also the extra time required for an additional treating step isavoided by the present invention. Furthermore, the effectiveness of thecombined .cleaning and activatingv solution is greater than thatprocessed by separate applications of a cleaning solution and anactivating solution.

Both the alkaline cleaner andthe activating composition may bereplenished from time to time as they areused up. The proportion 'ofactivated composition tov cleaner may be Areadily v.detelrriirled. fromexprience forV metal pf-aegiven .degree of cleanliness and a combinedsal t `or the like may be added that Areplenishes.bcth,in

the proportions in which they are used up. vSince certain changes may bein :the above linvention and. different embodiments ofthe ine ventionmay be made without departing from the scope hereof, it is intended thatall matter contained in the disclosure shall'be interpreted asillustrative and not in a limiting sense.

I claim as my invention:

1. An aqueous composition suitable vfor hot treating the surface of ametal selected from the group consisting of iron, zinc, cadmium,

aluminum and alloys in which these metals ypredominate to providefiorvsimultaneoiusly cleaning and activating-the surfaceitherein forexpediting the subsequent formation of protective coatings thereon,consisting of (a) between 0.1%

and by weight of the dried residue of an,

activating composition derived by dissolving in Water from 0.005% to byweight of a water :soluble compound of at least one ofthe group ofmetals consisting of titanium, zirconium, .lead and tin and the balancebeing disodium yorthophosphate, and evaporating the solution so,produced to dryness, (b) from 2% `to 50%, based on the weight of the driedresidue, of a water group consisting `of iron, zinc, cadmium, aluminumand alloys in which these metals predominate to provide forsimultaneouslycleaning Vand activating the surfaces therein forexpediting the subsequent formation of .protective coatings thereon,consisting of (a) between 0.1% andf10% by Weight of the dried residue ofan activating composition derived by dissolving in `water'from 0.005% to20% by weight of a Water soluble vcompound of at least one of the groupyof metals consisting of titanium, zirconium, lead and tin and thebalance being disodium orthophosphate,l

and evaporating the'solution so produced to dryness, (b) from 2% to50%,'based onthe weight of the dried residue, of a water soluble organicacid having a carboxyl radical attached `directly to an aliphatic groupto stabilize 4the activating composition, (c) an alkalinecompositionincluding substantial amounts of at least onealkali metal compound from.the groupconsisting of phosphates, silicates and carbonates,thealkaline composition being suitable for'cleaning metal surfaces in anamount to provide a @pH of from 10 to 12.5 in the aqueous composition,and the balance being water.

3. An aqueous composition suitable for hot treating the surface of ametal selected from the group consisting of iron,l zinc,cadmium-aluminum and alloys in which these metals,y predominate toprovide for simultaneously cleaning and activating the surfacesthereinfor expediting the. subsequent formation of protective coatingsthereon, consistingV of (al) betWeen-f,0.1%pand :10% by weightiofthedried residue ofan activating composition derived by dissolvingin-water `from f0.005% to1 20% byweightof a gwatervsolu-..=.ble1comp.0und. ofrtat least lone ofthe rgroup of metalslconsistingfof titanium, zirconium, lead andtinandjthe .balance beingdisodiumorthophosphate,,and,evaporating the solution so producedtorlryriessl (b) ,fromr2% to 50%, based Lonfthe .weightQfthadriedresidue, of a water solubleorganic acid having a carboxylradical attached directly-.to `an aliphatic group to stabi- -lize theactivating ..composition, (c) an alkaline composition, including asubstantial proportion -ofan-,amine soap, the alkaline composition be-;ing,suitable for cleaning metal surfaces in an amountto providea pH offrom 10 to 12.5 in the aqueous composition, andthebalance being Water. lf

4. Acompositioncomposed of (a) from 0.10

to 10,partsby weight of the activating composi- .tion derived bydissolving in water from 0.005% -to 20% vby Weight of atleast one watersoluble .compound of ametal from the group consisting of titanium,zirconium, lead and tin, and the balance being disodium orthophosphate,and

evaporating the solution to dryness, (b) from 0.002 to 5 partsbyweightof a water.l soluble orgarlic acidfhavng carboxyl group attacheddirectly to an aliphatic group, the amount of the organic acid beingbetween 2% and 50% by weight of theiactivating composition, and (c)vfrom 2to20 parts by weight of an alkaline compositionvselected from thegroupconsisting of .alkaline a1- Akali metal compounds, ammonia soapsand amine soaps capable of cleaning .metal when dissolved in ,-water,the alkaline composition. being present in an amount to produce a pH offrom l0 to 12.5 when 4 to 10 ounces of the entire composition isdissolved in a gallon of water.

5. A composition composed of (a) from 0.10 to v10 parts by weighty ofthe activating composition derived by dissolvingin water from 0.005% to20% by Weight of atleast one water soluble compound Aof -ametal from thegroup consistingv of titanium,v zirconium, ylead and tin, andthe balancebeing disodium orthophosphate, and evaporating thesolutionto dryness,(b) from 0.002 to 5 parts by Weight of a water soluble organic acidlhaving a carboxyl group attached directly to an `aliphatic group,theamountv of the organic acid .in water, thealkaline composition beingpresent in.l an amount torproduce arpH of from 10 to 12.5 when 4 to 1,0ounces `of the entire composition is dissolved in a galloriof water.

6. A. composition composed of (a)` from 0.10 to 10 partsibyweight oftheactivating composition derivedby dissolving in water from'f0.005% to20% by Weightpf-atleast one water soluble compoundof a metal from thegroup consisting of Ytitanium,-.zirconium, lead and tin, -and thebalance beingdisodium orthophosphate, and evaporating the solution to,dryness, .(b) from 0.002to .5 partsby weight of aI waterv solubleorganic acid having a: carboxyl. group attached directly to an aliphaticgroup; the amount of the organic acid. being between 21%. and 50% byweight of 44the activating composition, and (c) from 2 to 20. parts vby-weightzof an alkaline composition yincludingan aminesoap, the alkalinecomposition beingl capable .of cleaning metal when dissolvedgnwfwater,,thealkalme composition being 9 present in an amount to produce a pH offrom 10 to 12.5 when 4 to 10 ounces of the entire composition isdissolved in a gallon of Water.

7. In the process of applying phosphate coatings on metals, whereinsimultaneous cleaning and activating of the surfaces of metals from thegroup consisting of iron, zinc, cadmium, aluminum and alloys in whichthese metals predominate is effected to enhance the subsequent formationof protective phosphate coatings thereon, the step comprising applyingto the metal surface 'a hot aqueous solution consisting of (a) between0.1% and 10% by weight of the dried residue of an activating compositionderived by dissolving in water from 0.005% to by weight of a Watersoluble compound of at least one of the group of metals consisting oftitanium, zirconium, lead and tin and the balance being disodiumorthophosphate, and evaporating the solution so produced to dryness, (b)from 2% to 50%, based on the weight of the dried residue, of a watersoluble organic acid having a carboxyl radical attached directly to analiphatic group to stabilize the activating composition, (c) an alkalinecomposition selected from the group consisting of alkaline alkali metalcompounds, ammonia soaps and amine soaps suitable for cleaning metalsurfaces, in an amount to provide a pH of from 10 to 12.5

in the aqueous composition, and the balance be- ,i

ing Water.

8. In the process of applying phosphate coatings on metals, whereinsimultaneous cleaning and activating of the surfaces of metals from thegroup consisting of iron, zinc, cadmium, alurninum and alloys in whichthese metals predominate is effected to enhance the subsequent formationof protective phosphate coatings thereon, the step comprising applyingto the metal surface a hot aqueous solution consisting of (a) between0.1% and 10% by weight of the dried residue of an activating compositionderived by dissolving in water from 0.005% to 20% by weight of a Watersoluble compound of at least one of the group of metals consisting oftitanium, zirconium, lead and tin and the balance being disodiumorthophosphate, and evaporating the solution so produced to dryness, (b)from 2% to 50%, based on the weight of the dried residue, of a watersoluble organic acid having a carboxyl radical attached directly to analiphatic group to stabilize the activating composition, (c) an alkalinecomposition selected from the group consisting of alkaline alkali metalcompounds, am-

monia soaps and amine soaps suitable for cleaning metal surfaces, in anamount to provide a pH of from 10 to 12.5 in the aqueous composition,and the balance being water, the aqueous solution being at a temperatureof between F. and the boiling point, the organic acid enabling the acti-Vating composition to function at the high temperature for long periodsof time.

9. The process of simultaneously cleaning and activating the surfaces ofmetals from the group consisting of iron, zinc, cadmium, aluminum andalloys in which these metals predominate, to enhance the subsequentformation of protective phosphate coatings thereon comprising applyingto the metal surface a hot aqueous solution consisting of (a) between0.1% and 10% by weight of the dried residue of an activating compositionderived by dissolving in Water from 0.005% to 20% by weight of a watersoluble compound of at least one of the group of metals consisting oftitanium, zirconium, lead and tin and the balance being disodiumorthophosphate, and evaporating the solution so produced to dryness, (b)from 2% to 50%, based on the weight of the dried residue, of a watersoluble organic acid having a carboxyl radical attached directly to analiphatic group to stabilize the activating composition, (c) an alkalinecomposition selected from the group consisting of alkaline alkali metalcompounds, ammonia soaps and amine soaps suitable for cleaning metalsurfaces, in an amount to provide a pH of from 10 to 12.5 in the aqueouscomposition, and the balance being Water, the aqueous solution being ata temperature between 160 F. and the boiling point, the organic acidenabling the activating composition to function at the high temperaturefor longer periods of time, and immediately thereafter applying to thecleaned and activated metal surfaces a phosphate coating compositioncomprising a solution of phosphoric acid, phosphates and .an oxidizingagent to produce a protective phosphate coating thereon.

JOI-IN C. LUM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTSy

8. IN THE PROCESS OF APPLYING PHOSPHATE COATINGS ON METALS, WHEREINSIMULTANEOUS CLEANING AND ACTIVATING ON THE SURFACES OF METALS FROM THEGROUP CONSISTING OF IRON, ZINC, CADMIUM, ALUMINUM AND ALLOYS IN WHICHTHESE METALS PREDOMINATE IS EFFECTED TO ENHANCE THE SUBSEQUENT FORMATIONOF PROTECTIVE PHOSPHATE COATING THEREON, THE STEP COMPRISING APPLYING TOTHE METAL SURFACE A HOT AQUEOUS SOLUTION CONSISTING OF (A) BETWEEN 0.1%AND 10% BY WEIGHT OF THE DRIED RESIDUE OF AN ACTIVATING COMPOSITIONDERIVED BY DISSOLVING IN WATER FROM 0.005% TO 20% BY WEIGHT OF A WATERSOLUBLE COMPOUND OF AT LEAST ONE OF THE GROIUP OF METALS CONSISTING OFTITANIUM. ZIRCONIUM, LEAD AND TIN AND THE BALANCE BEING DISODIUMORTHOPHOSPHATE, AND EVAPORATING THE SOLUTION SO PRODUCED TO DRYNESS, (B)FROM 2% TO 50%, BASED ON THE WEIGHT OF THE DRIED RESIDUE, OF A WATERSOLUBLE IORGANIC ACID HAVING A CARBOCYL RADICAL ATTACHED DIRECTLY TO ANALIPHATIC GROUP TO STABLIZE THE ACTIVATING COMPOSITION, (C) AN ALKALINECOMPOSITION SELECTED FROM THE GROUP CONSISTING OF ALKALINE ALKALI METALCOMPOUNDS, AMMONIA SOAPS AND AMINE SOAPS SUITABLE FOR CLEANING METALSURFACES, IN AN AMOUNT TO PROVIDE A PH OF FROM 10 TO 12.5 IN THE AQUEOUSCOMPOSITION, AND THE BALANCE BEING WATER, THE AQUEOUS SOLUTION BEING ATA TEMPERTATURE OF BETWEEN 160*F. AND THE BOILING POINT, THE ORGANIC ACIDENABLING THE ACTIVATING COMPOSITION TO FUNCTION AT THE HIGH TEMPERATUREFOR LONG PERIODS OF TIME.